Surface reaction of bioactive and ferrimagnetic glass-ceramics in the system FeO-Fe2O3-CaO-SiO2

A bioactive and ferrimagnetic glass-ceramic in which magnetite is dispersed in a CaO, SiO2-based matrix is obtained by a heat treatment of 40Fe(2)O(3), 29CaO, 31SiO(2), 3B(2)O(3), 3P(2)O(5) (in weight ratio) glass. This kind of glass-ceramic is useful as thermoseeds for hyperthermia treatment of cancer, The apatite layer, the origin of the bioactivity which is formed on its surface in living body, is however, liable to be peelled off after a long period, since the matrix is soluble to form a mechanically weak reaction layer under the apatite layer in the body environment, In order to obtain bioactive and ferrimagnetic glass-ceramic which is stable for a long period in living body, modification of the composition of the glass-ceramic was attempted, It was found that the composition of 40Fe(2)O(3), 32CaO, 31SiO(2), 3P(2)O(5) (in weight ratio) gives a magnetite-containing glass-ceramic which forms the apatite layer on its surface without forming a mechanically weak reaction layer in the simulated body fluid.